Similar to tuples, a generator _can_ be parenthesized or
unparenthesized. Only search for bracketed comments if it contains its
own parentheses.
Closes https://github.com/astral-sh/ruff/issues/7623.
## Summary
The tokenizer was split into a forward and a backwards tokenizer. The
backwards tokenizer uses the same names as the forwards ones (e.g.
`next_token`). The backwards tokenizer gets the comment ranges that we
already built to skip comments.
---------
Co-authored-by: Micha Reiser <micha@reiser.io>
## Summary
Given a trailing operator comment in a unary expression, like:
```python
if (
not # comment
a):
...
```
We were attaching these to the operand (`a`), but formatting them in the
unary operator via special handling. Parents shouldn't format the
comments of their children, so this instead attaches them as dangling
comments on the unary expression. (No intended change in formatting.)
## Summary
Given a statement like:
```python
result = (
f(111111111111111111111111111111111111111111111111111111111111111111111111111111111)
+ 1
)()
```
When we go to parenthesize the target of the assignment, we use
`maybe_parenthesize_expression` with `Parenthesize::IfBreaks`. This then
checks if the call on the right-hand side needs to be parenthesized, the
implementation of which looks like:
```rust
impl NeedsParentheses for ExprCall {
fn needs_parentheses(
&self,
_parent: AnyNodeRef,
context: &PyFormatContext,
) -> OptionalParentheses {
if CallChainLayout::from_expression(self.into(), context.source())
== CallChainLayout::Fluent
{
OptionalParentheses::Multiline
} else if context.comments().has_dangling(self) {
OptionalParentheses::Always
} else {
self.func.needs_parentheses(self.into(), context)
}
}
}
```
Checking for `self.func.needs_parentheses(self.into(), context)` is
problematic, since, as in the example above, `self.func` may _already_
be parenthesized -- in which case, we _don't_ want to parenthesize the
entire expression. If we do, we end up with this non-ideal formatting:
```python
result = (
(
f(
111111111111111111111111111111111111111111111111111111111111111111111111111111111
)
+ 1
)()
)
```
This PR modifies the `NeedsParentheses` implementations for call chain
expressions to return `Never` if the inner expression has its own
parentheses, in which case, the formatting implementations for those
expressions will preserve them anyway.
Closes https://github.com/astral-sh/ruff/issues/7370.
## Test Plan
Zulip improves a bit, everything else is unchanged.
Before:
| project | similarity index | total files | changed files |
|--------------|------------------:|------------------:|------------------:|
| cpython | 0.76083 | 1789 | 1632 |
| django | 0.99981 | 2760 | 40 |
| transformers | 0.99944 | 2587 | 413 |
| twine | 1.00000 | 33 | 0 |
| typeshed | 0.99983 | 3496 | 18 |
| warehouse | 0.99834 | 648 | 20 |
| zulip | 0.99956 | 1437 | 23 |
After:
| project | similarity index | total files | changed files |
|--------------|------------------:|------------------:|------------------:|
| cpython | 0.76083 | 1789 | 1632 |
| django | 0.99981 | 2760 | 40 |
| transformers | 0.99944 | 2587 | 413 |
| twine | 1.00000 | 33 | 0 |
| typeshed | 0.99983 | 3496 | 18 |
| warehouse | 0.99834 | 648 | 20 |
| **zulip** | **0.99962** | **1437** | **22** |
## Summary
This PR adds the `--preview` and `--no-preview` options to the `format` command (hidden) and passes it through to the formatte.
## Test Plan
I added the `dbg(f.options().preview())` statement in `FormatNodeRule::fmt` and verified that the option gets correctly passed to the formatter.
## Summary
This PR adds comment handling for comments between the `=` and the
`value` for keywords, as in the following cases:
```python
func(
x # dangling
= # dangling
# dangling
1,
** # dangling
y
)
```
(Comments after the `**` were already handled in some cases, but I've
unified the handling with the `=` handling.)
Note that, previously, comments between the `**` and its value were
rendered as trailing comments on the value (so they'd appear after `y`).
This struck me as odd since it effectively re-ordered the comment with
respect to its closest AST node (the value). I've made them leading
comments, though I don't know that that's a significant improvement. I
could also imagine us leaving them where they are.
## Summary
As a small quality-of-life improvement, the locator can now slice like
`locator.slice(stmt)` instead of requiring
`locator.slice(stmt.range())`.
## Test Plan
`cargo test`
## Summary
The motivation here is that this enables us to implement `Ranged` in
crates that don't depend on `ruff_python_ast`.
Largely a mechanical refactor with a lot of regex, Clippy help, and
manual fixups.
## Test Plan
`cargo test`
## Summary
This PR ensures that if an expression has an own-line leading comment
_before_ its open parentheses, we render it as such.
For example, given:
```python
[ # foo
# bar
( # baz
1
)
]
```
On `main`, we format as:
```python
[ # foo
(
# bar
# baz
1
)
]
```
As of this PR, we format as:
```python
[ # foo
# bar
( # baz
1
)
]
```
## Test Plan
`cargo test`
